Paper machine felts

Abstract

The present invention relates to a felt for use in papermaking machines showing enhanced resistance to degradation in the presence of peroxide which felt comprises a woven base and a sheet contracting layer attached thereto characterized in that at least one of said layer and said woven base comprises fibers of polyamide 12, 12 found by extrusion of a melt of polyamide 12, 12 having intrinsic viscosity of not less than 0.65 dl/gram.

We claim: 
     
       1. A felt for use in papermaking machines comprising a woven base and at least one batt fibre needled thereto characterised in that at least one of said batt fibre and said woven base comprises fibres of polyamide 12,12 formed by extrusion of a melt of polyamide 12,12 having intrinsic viscosity of not less than 0.65 dl/gram. 
     
     
       2. A felt as claimed in claim 1 characterised in that the melt of polyamide 12,12 contains 0.2 to 1.0% by weight of an antioxidant. 
     
     
       3. A felt as claimed in claim 2 characterised in that the melt of the polyamide 12,12 contained 0.4 to 0.6% by weight of an antioxidant. 
     
     
       4. A felt as claimed in claim 3 characterised in that the antioxidant is selected from one or more of alphatocopherol and related structures, condensation products of diphenylamine and acetone, and of diphenylamine and a compatible phenolic stabliser with amide functionality. 
     
     
       5. A felt as claimed in claim 2 wherein the addition of antioxidant is added at or before extrusion. 
     
     
       6. A felt as claimed in claim 1 characterised in that the felt comprises a woven base including monofilaments of polyamide 12,12 having an intrinsic viscosity of not less than 0.60 dl/gram. in either the warp direction or the shute direction. 
     
     
       7. A felt as claimed in claim 1 wherein filaments or monofilaments of polyamide 12,12 are drawn and subject to a controlled relaxation after drawing. 
     
     
       8. A felt as claimed in claim 7 wherein the relaxation step comprises a relaxation within the range of 5% to 15%.